Orbital Disease

Dogs and cats sometimes develop disease within the orbit of the skull (where the eyeball is). Besides the eye itself, there are other structures in the orbit that can become diseased. This includes some salivary glands, tear-producing glands, nerves, blood vessels, and even the bone itself! The bony wall of the orbit separates it from the nasal and sinus cavities, and diseases in these areas have the potential for eroding through that wall into the orbit.

Many dogs and cats with orbital disease may first be referred to the ophthalmologist, because the eye may appear to be protruding abnormally. In other cases the patient may first be seen by an internist or surgeon because of apparent discomfort on opening the mouth (the back part of the mandible or jawbone actually rises vertically behind the orbit, and when the jaw is opened this part of the mandible rotates forward, pressing on the back of the orbit). In some instances orbital disease may be picked up during a dental procedure, since some diseases may extend downward from the orbit to the back part of the mouth.

The two most common orbital diseases are infections and tumors. The former may be successfully treated by establishing drainage (often through the back of the mouth) and antibiotics based on a culture of the offending germs. Sometimes a tooth root infection may be the cause and a tooth extraction required. There are many potential tumors that can arise from or spread to the orbit. Treatment depends on determining the tumor type, predicting its biological behavior (tendency to recur in the same spot and/or tendency to spread to other locations in the body), and deciding if the tumor can be surgically removed. It is always desirable to save the eye itself whenever possible, but in some instances successful treatment will require removal of the affected eye.

Determining the cause or orbital disease, establishing the extent of disease, and treatment planning are best guided by diagnostic imaging. Radiographs (x-rays) are the least helpful generally. Ultrasound can be more helpful, but still provides insufficient information in most cases for complete planning purposes. The best tools for imaging are CT and MRI scanning. If your pet is suspected of having an orbital disease there is a good likelihood that the specialist will recommend one of these advanced diagnostic imaging methods.

Surgery for orbital disease, including tumors, can often be successful. In many cases the operation may be done by a team that includes a surgeon and an ophthalmologist. The pre-operative MRI or CT is used to guide the operation. Depending on the underlying disease, adjuvant treatment in the form of radiation therapy or drug therapy (or both) may be indicated.